P-DMX Intro

The P-DMX concept is simply sending power and DMX data over a single CAT5 cable for distribution to remote display elements.
Running cables out to intelligent display elements can be a hassle as you usually need both power and data cables. With P-DMX, the power and DMX data are in the one cable, simplifying set up. The DC power sent over the CAT5 cables is 24V - 48V. Most display elements require 5V or 12V DC, so each P-DMX controller includes a step-down voltage converter. Because the voltage on the CAT5 cable is much higher, the current load on that cable is correspondingly lower, ensuring lower losses in the cabling. It also means that variations in the power supply voltage are automatically compensated for by the PoDMX controller.

Each P-DMX (CAT5) cable is rated for approximately 40W - 80W of DC power. (varies with supply voltage) This means each P-DMX controller can supply up to about 12 Amps @ 5V (or 5 Amps @ 12V) to it's load (lights, etc). This is much better than trying to draw those high currents via conventional cables and loosing up to half of it in the process. Because the voltage is regulated right at the P-DMX controller, the 5V (or 12V) is much more stable.

P-DMX controllers will become available in many varieties. Some will be pixel drivers, others will be able to drive servos for animatronics. Flood and spots lights with integrated P-DMX controllers will also be possible.

Not all P-DMX components will be suitable for the entire (24V - 48V) input voltage range. Some may be limited to 24V for example due to design and cost constraints. As long as you keep this in mind and choose a suitable DC power supply for the P-DMX distributor, all will be well. The P-DMX system can deliver the most power (80W) to each output when the supply voltage is 48V. Lowering the DC supply voltage will reduce its capability to 60W @ 36V or 40W @ 24V. Even at 24V, 40W is enough power to drive 100 x WS2801 pixels (30W) and still have enough for the drive electronics and an 80% efficient step-down regulator.

Contents

Layout

This is an overview of how the various P-DMX items fit together.

Here's an example of one output of the P-DMX distributor connected to several P-DMX controllers in daisy chain style. The incoming power and DMX data feeds to the P-DMX distributor are not shown, but are as per the diagram above.